1. Field of the Invention
The present invention generally relates to a working apparatus. More specifically, the present invention relates to an apparatus which is operative to cause movements in both X-direction and Y-direction in working heads so as to perform various works.
2. Description of the prior art
Automatic apparatus having movable working heads are well-known and used in various fields. They are basically cartesian-coordinates robots, and have working heads at their hand portions. Japanese Patent Laid-open Nos. Hei 1-177930 and 2-78300, and Japanese Utility Model Laid-open No. Sho 63-147230 disclose such apparatuses.
Though the apparatuses disclosed in Japanese Patent Laid-open No. Hei 1-177930 and Japanese Utility Model
Laid-open No. Sho 63-147230 adopt a system utilizing a belt for pulling a working head in order to cause movements in X-direction and Y-direction, such system is not suitable for high-accuracy positional adjustment. For this reason, ball-screw is used in many apparatuses. However, the use of ball-screws does not ensure 10-micron-level positional accuracy. Furthermore, it is almost impossible to attain micron-order accuracy through conventional machine elements.